Currently, a mobile communication system such as a mobile phone system is used widely. In addition, in order to achieve further speed improvement and capacity enlargement of radio communication, active discussion is carried out continuously with respect to a next-generation mobile communication technology. For example, in international standardization organization 3GPP (3rd Generation Partnership Project), a standard referred to as LTE (Long Term Evolution) is proposed (See, for example, 3rd Generation Partnership Project, “Evolved Universal Terrestrial Radio Access (E-UTRA); Physical Channels and Modulation”, 3GPP TS 36.211 V9.1.0, 2010-03, 3rd Generation Partnership Project, “Evolved Universal Terrestrial Radio Access (E-UTRA); Physical layer procedures”, 3GPP TS 36.213 V9.1.0, 2010-03. and 3rd Generation Partnership Project, “Evolved Universal Terrestrial Radio Access (E-UTRA); Radio Resource Control (RRC); Protocol specification”, 3GPP TS 36.331 V9.2.0, 2010-03). In addition, a standard referred to as LTE-A (Long Term Evolution-Advanced) with LTE extended is also proposed (See, for example, 3rd Generation Partnership Project, “Feasibility study for Further Advancements for E-UTRA”, 3GPP TR 36.912 V9.0.0, 2009-09).
In a mobile communication system, a relay station which relays communication between a base station and a mobile station may be provided. By providing a relay station, expansion of a cell coverage and enhancing of a throughput or the like may be achieved. However, in the relay station, interference (self-interference) may arise between a reception signal and a transmission signal of its own station. For example, when a frequency band used between the base station and the relay station and a frequency band used between the relay station and the mobile station are overlapped, there is a possibility that a radio signal transmitted to the mobile station sneaks into a reception circuit of its own station, and the radio signal may not be received normally from the base station. Then, it is proposed that the relay station adjusts a timing for performing communication with the base station and a timing for performing communication with the mobile station, and suppresses the self-interference (See, for example, Section 9 of 3rd Generation Partnership Project, “Feasibility study for Further Advancements for E-UTRA”, 3GPP TR 36.912 V9.0.0, 2009-09).
In addition, in a mobile communication system, when a mobile station is in a standby state, there is a method for achieving power-saving of a mobile station by limiting the timing for receiving a radio signal from a base station. For example, the mobile station receives periodically a paging channel which the base station transmits at a timing agreed between the base station and the mobile station in advance, and at the other timings, stops the reception processing. The base station, when performing calling with respect to the mobile station, transmits paging information indicating a mobile station of calling destination by the paging channel. The mobile station, when receiving the paging channel and detecting a call for its own station, resumes data communication (See, for example, Section 5.3.2 of 3rd Generation Partnership Project, “Evolved Universal Terrestrial Radio Access (E-UTRA); Radio Resource Control (RRC); Protocol specification”, 3GPP TS 36.331 V9.2.0, 2010-03).
Meanwhile, in a mobile communication system where a base station and a mobile station perform communication through a relay station, a case where the relay station performs a handover for switching a base station of connection destination may be considered. For example, when the relay station is mounted on a vehicle such as a train or a car, and the mobile station is carried by a passenger of the vehicle and performs communication through the relay station, a situation where although a handover for switching a connection destination of the mobile station does not arise, a handover for switching a connection destination of the relay station arises may be considered.
However, in that case, an influence which the handover of the relay station exerts on the mobile station which is in a state of performing a reception processing intermittently becomes a problem. For example, a transmission timing of a paging channel to be received by the mobile station may be different depending on the base station. Consequently, when the relay station performs the handover, the timing for transferring the paging channel to the mobile station may also be changed. The mobile station which is in an intermittent receiving state, after the occurrence of handover in the relay station, even when trying to receive the paging channel at the same timing as that before the handover, may fail in the reception. It may be considered that the mobile station which has failed in reception of the paging channel, determining that the mobile station has moved outside a serving area of the relay station, repeats processing of cell searching or the like, for example. Consequently, there is a problem that time is needed until the mobile station returns to the state of receiving the paging channel intermittently, and an electric power consumption increases.